Typically, a DMOS (double diffused MOS) transistor is used as a power transistor for a high voltage power integrated circuit. The DMOS transistor supplies a large amount of current per unit area to a position requiring low forward voltage drop.
The DMOS transistor can be a trench DMOS transistor in which a channel is vertically formed and a gate is formed in a trench extending between a source and a drain. The trench DMOS transistor provides low on-resistance.